200k views
1 vote
Find the center and radius of the circle x^2 + y^2 - 6y - 16 = 0

User Khanh
by
8.7k points

1 Answer

4 votes

Answer: (0, 3)

Explanation:

You need to put the equation in the circle formula. In order to do that, you need to complete the square.

(x-h)² +(y-k)² = r² where (h,k) is the center

Your equation:

x²+y²-6y-16 = 0 bring over constants to other side

x²+y²-6y = 16 complete the square by taking the y term (6) divide by 2 and square that number to add to both sides


((6)/(2) )^(2) = 3² = 9 this is the completion of square for the y quadratic part

add to both sides of equation

x²+y²-6y+9= 16 +9

x²+y²-6y +9= 25 factor the y quadratic part

you get (y-3)(-3) = (y-3)²

x²+(y-3)² = 16 we have put it in the format above (x-h)² +(y-k)² = r²

there is no x so h=0 k=3

so the center is (0,3)

User RTA
by
8.3k points